1. Field
a magnetic sensing element is provided.
2. Related Art
Japanese Unexamined Patent Application Publication Nos. 2003-218428, 2005-51251, 2004-348850, and 2004-214251 each disclose a current-perpendicular-to-plane-mode magnetic sensing element (CPP-mode magnetic sensing element) including a free magnetic layer composed of a Heusler alloy such as Co2MnGe.
It has been known that the free magnetic layer composed of Co2MnGe increases the product ΔRA of the rate of change of magnetoresistance ΔR and an element area A. The increase in the product ΔRA is a significantly important requirement for the practical application of a CPP-mode magnetic sensing element having a higher recording density.
When the free magnetic layer is composed of Co2MnGe, an interlayer coupling magnetic field Hin acting between the pinned magnetic layer and the free magnetic layer increased. Although a Ge concentration of about 25 atomic percent increased ΔRA, the interlayer coupling magnetic field Hin also increased disadvantageously. Although a Ge content exceeding 25 atomic percent slightly reduced ΔRA, the interlayer coupling magnetic field Hin increased steeply. The increase in interlayer coupling magnetic field Hin results in an increase in asymmetry. Thus, it is necessary to reduce the interlayer coupling magnetic field Hin.
The free magnetic layer composed of Co2MnGe has relatively high coercive force and magnetostriction. Thus, to improve the stability of the read characteristics, preferably, these magnetic properties are also minimized.